Ski pole

ABSTRACT

The invention is directed to a ski pole comprising a longitudinal shaft. The shaft includes a cross-section that comprises:
     a first part including a curved first portion arranged symmetric about a cross-sectional centerline (CL) of the shaft, and   a second part including a second portion arranged symmetric about the cross-sectional centerline.   

     Wherein the first part is connected to the second part by side parts including side portions, each side part comprises a first end connected to an end of the first part and a second end connected to an end of the second par, each connection between the side parts and the first and second parts forms a corner, such that there are total four corners in the cross-section of the shaft.

The present invention concerns a ski pole. More specifically, theinvention is directed to a favorable ski pole comprising a longitudinalshaft which has high breaking strength, stiff (low span) and withaerodynamically properties without increasing the weight of the shaft.

BACKGROUND

Hand held ski poles have been used together with skies for centuries,primarily for helping the skier maintain balance when skiing, but alsoto help the skier get traction for movement in a forward direction. Whenmodern skiing was in its infancy almost 200 years ago, a single pole wasoften used. However, in modern skiing two ski poles are used both fordownhill and cross-country skiing.

As modern skiing is constantly developing, focus is put on thedevelopment of new and improved skiing equipment to further advance thesport. Ski poles have been transformed fundamentally from the singlepole of the 19^(th) century to the light weight versions of today, whenthe skier carries one ski pole in each hand.

Traditionally, the typical cross-country ski pole, and also the downhillversions of the poles, has a shaft made from resin-bound fiber layerswhich provide the walls surrounding the continuous cavity of the shaft.

In racing ski poles, the fibers primarily comprise carbon fibers whilethe general-purpose ski poles usually employ glass fiber or acombination of carbon and glass fibers. The binder resin comprises e. g.an epoxy resin or a polyester resin. It is prior known to make across-sectionally circular pole shaft downward tapered so as to placeits center of gravity higher up, i.e. to provide a lightweight lower endand a low air resistance for the lower end.

The traditional ski pole comprises a circular cross-section hollow shaftfitted with a handle, a disc or a snow guard for keeping the pole fromsinking too far into the snow, and a spike in the bottom end to ensuretraction.

The circular-and/or elliptic shaped cross-section of the shaft, producea drag and/or a lift when the skier push them forward into a pendulummovement. This drag/lift causes the ski pole to wander off to eitherleft or right. This drag force deviation from a strict pendulum movementhas the disadvantage that the skier must use unnecessary force tocorrect the trajectory of the ski pole into a strictly forward directedmotion. This drag effect is small and may barely be noticeable to anexerciser. But to a professional athlete, every second, even tenths andhundreds counts, since very often competitions are decided by very smallmargins.

The publication US 5611571 A discloses a pole shaft for a cross-countryski pole having a circular cross-section that changes progressivelydownwards into a droplet shape and, below the mid-way point of theshaft, the length of the droplet shape in relation to its widthincreases while the cross-sectional area diminishes. By virtue of thedroplet shape, the ski pole can be given more rigidity in skiingdirection, whereby the bottom end of the pole can be made lighter whileimproving the aerodynamics of the pole. The droplet shape of thecross-section may provide better aerodynamics, but it simultaneouslyprovides a ski pole with increased weight and unstable in use.

The publication EP 2308 569 A1 discloses a ski pole having a triangularcross-section. The substantially triangular cross-sectional shape isstiff (low span), has high breaking strength and reduces some of thedrag forces compared to circular cross-section. The ski pole is arrangedwith one of the three sides of the triangular shape of the pole facingdirectly forward into the direction of movement of the skier holding theski pole. Furthermore, the substantially triangular cross-sectionalshape of the ski pole requires less material to be used to produce thepole as compared to a ski pole with a circular cross-section and aretherefore considerably lighter in weight.

However, as the sport of skiing is constantly developing, there is aconstant search and demand for improved solutions to provide new skipoles which are better suited to the sport of skiing and which may givethe athlete benefits of hundreds, tenths or seconds during a race.

A pole shaft is required to have a certain strength especially againstbuckling, which constrains possibilities for the reduction of weight anddiameter.

Thus, the object of the invention is to provide a pole shaft for a skipole that is stiffer (lower span) than the prior arts pole shaft, withhigher breaking strength (pull to limit) than the prior art pole shaftand with aerodynamic properties without compromising very much or atleast within certain defined perimeters, in weight and diameter.

SUMMARY OF THE INVENTION

The present invention is directed to a ski pole comprising alongitudinal shaft. The shaft includes a cross-section shape thatcomprises:

-   a first part including a curved first portion arranged symmetric    about a cross-sectional centerline (CL) of the shaft, and-   a second part including a second portion arranged symmetric about    the cross-sectional centerline (CL).

The first part is connected to the second part by side parts includingside portions, each side part comprises a first end connected to an endof the first part and a second end connected to an end of the secondpart, each connection between the side parts and the first and secondparts forms a corner, such that there are total four corners in thecross-section of the shaft.

The ski pole may be a longitudinal hollow shaft. The walls surroundingthe shaft cavity can be of equal thickness or the wall thickness mayfluctuate over various sections of the shaft length. The wall thicknessviewed in cross-section may provide an inner and outer perimeter of thecross-section. The inner and outer perimeter may have same orsubstantially same shape.

The terms “first part”, “second part”, “side parts”, “first portion”,“second portion” and “side portions” may relate to sides of thecross-sectional shape of the ski pole. Preferably, the terms aredirected to the sides of the outer perimeter of the cross-section of theshaft. The above terms may also be illustrated by a line, each linehaving an end or edge, i.e. staring point and end point. The end or edgedefining the end of one line and the beginning of another line. Forexample, the end of the first portion and beginning of the side portion.

The corner is a point where converging lines, edges or ends between thefirst, second and side parts or portions meet. Thus, the corner is theangular part or space between meeting lines, edges or ends of the first,second and side parts and portions and is situated near the vertex ofthe angle.

The four corners of the present invention are formed at the intersectionbetween the ends of the first part with the first ends of the sideparts, and the ends of the second part with the second ends of the sideparts.

The curved portion may be referred to as a curved line which is adeviation from a straight line without sharp breaks or angularity.

The first part may include a straight or another secondary curvedportion connected to the curved portion such that they togetherconstitute the first part. The first part may constitute only one curvedportion.

The same applies to the second part, which may constitute a secondarycurved and/or straight portion connected to the second portion such thatthey together constitute the second part. The second part may constituteonly one second portion, where the second portion may be a straightpotion or a curved portion.

The side parts may constitute a straight portion and/or a curved portionor a combination thereof.

The curved portions may be curved inwards towards the center of thecross-section, or the curved portions may be curved outwards with thepeak of the curved directed outward from the center of thecross-section.

Each connection between the side parts and the first and second partsforms a corner, wherein the corner may be rounded such that there are nosharp edges for better aerodynamic properties.

In terms of strength and aerodynamics, the optimum solution for a skipole is achieved according to the invention in a manner such that thecross-section comprises a first part having a curved portion, a secondpart having a second portion and wherein the first and second parts areconnected by side parts providing four corners at the connectionsbetween the different parts.

The longitudinal shaft of the ski pole may gradually change in diameterand/or shape towards the lower section of the shaft.

The first part, the second part and the side part may be arrangedsymmetric about the cross-sectional centerline parallel to the moving(forward) direction of the skier. The entire cross-section of the shaftmay be symmetric about the centerline (CL).

The first part may be a front part and the second part may be a backpart of the cross section of the ski pole viewed in the moving directionof the skier.

The curved portion or the curved line of the first part may be shaped asan arc.

The curved portion or the curved line of the first part may be acircular arc. A circular arc may be defined as a segment of a circle.

The length of an arc of a circle with radius (R, r) and subtending anangle θ (measured in radians) with the circle center, i.e., the centralangle, is:

L =θ * R

This is because:

$\frac{L}{\text{circumference}} = \frac{\theta}{2\text{π}}$

The curved first portion (L) may be defined by the angle θ and formspart of a circumference of a circle with radius (R,r). Thus, this meansthat all points of an outer perimeter of the cross-sectional shape ofthe shaft, may lie at or within a circumference of the circle withradius (R,r).

The curved first portion may be the arc of a semi-circle, or an arcwhich is less than the semi-circle or and arch which is greater than thesemi-circle.

In an embodiment of the invention, the angle θ may be less than 180degrees.

In another embodiment, the angle may be: 180° > θ > 160°.

In yet another embodiment, the length of the curved first portion (L)may be 3 radians (3 rad, or 3 times the radius).

The length of the second part may be equal or less than the radius (R)of the curved first portion. This means that the cross-sectional shapegradually narrows in from the curved first portion to the second part.

Furthermore, the two times radius (R,r) of the curved first portion maybe equal to the greatest width of the cross-section of the shaft. Thismeans the curved front portion defines a circular arc with radius (R,r),and that the greatest width of the cross-section of the shaft does notexceed the 2x radius (diameter) of the circle.

The curved first portion (circular arc) and each of the four corners mayall be located on, at or coincide with, an outer circumference of thecircle with the radius (R,r). Hence, each of the four corners are pointslocated on a circumference of the circle.

The side parts and the back part may be straight, curved lines or acombination thereof. In an embodiment, the back and side portions areslightly curved lines (curved outwards). Each point of the slightlycurved lines lies within the circumference of the circle with radius(R).

The curved first portion may be the front part of the ski pole, meaningthat it is headed forward in the skiing direction. Thus, the second partis the back part of the ski pole.

The second part may be the front part of the ski pole, meaning that itis headed forward in the skiing direction. Thus, the curved first partis the back part of the ski pole.

Test results shows that the above mentioned four corners cross-sectionalshape of a shaft, has surprisingly increased strength compared toexisting cross-sectional shapes, such as circular (round) or triangularshape. The test was performed by measuring the deformation (span) fordifferent cross-sectional shapes of shafts. The testing shafts whereapplied a predefined load N in order to measure their individual spanresulting from the load (force) N applied. Their individual span waslater compared. Low value of span means that the shaft is stiff and moreresistant to deformation.

Also “pull to limit tests” was performed where the individual shaftswhere tested by applying an increasing load N, until the shaft breaks.The higher load (max load) means higher breaking strength.

When studying the test results from the above-mentioned testes, theshaft with the four corners cross-sectional shape of the presentinvention has remarkable and surprisingly lower span (meaning; stiffer)compared to other cross-sectional shapes tested. In addition, the shaftof the present invention also has the higher breaking strength.

To measure the aerodynamics, which is also very important for a skier, atest in a wind tunnel was performed for indicating the drag coefficientof different cross-sectional shaped shafts. The drag coefficient is adimensionless quantity that is used to quantify the drag or resistanceof an object in a fluid environment, such as air or water. It is used inthe drag equation in which a lower drag coefficient indicates the objectwill have less aerodynamic or hydrodynamic drag. The drag coefficient isalways associated with a particular surface area.

The shaft was tested at 30, 45, 75, 90 and 105 km/h. Relevant speedduring skiing are up to 50 km/h, higher speed is mostly during downhillskiing where the poles are held in a backward direction and aretherefore not very relevant. In addition, different angles of the poleshave been measured such as 0, 45, 90 and 180 degrees. Where the angles 0and 45 are the most relevant angles of the wind in relation to theshaft. The test result shows that the curved first portion with aslightly rounded geometry of the side parts and second portion, hasbetter aerodynamic properties than the triangular shape at relevantspeed and angles. The four corners cross-section has consistently betteraerodynamically properties compared to the circular cross-sectionalshape.

Thus, the improved aerodynamics at relevant wind speed, may probablyprovide better pendulum characteristics, which skiers considers veryimportant for a ski pole.

Hence, the shaft for a ski pole of the present invention shows aremarkable and surprisingly combination of increased rigidity, breakingstrength and improved aerodynamics without increasing the weight of theshaft.

The invention is directed to a ski pole comprising a longitudinal poleshaft, in which the cross-section of said pole shaft in one end (top)has four corners, and in which the cross-section of said pole shaft inthe opposite end (bottom) is circular; the cross-section of said polegradually adopting a four corner shape to circular cross-section movingalong the ski pole from one end to the opposite end. The circular shapemay be provided at the lower part of the ski pole.

A pole shaft may be hollow and made from e. g. of longitudinal andtransverse fiber layers. The walls surrounding the shaft cavity can beof equal thickness or the wall thickness may fluctuate over varioussections of the shaft length.

It may be preferred that adjacent to the lower end of a shaft the fourcorner shape changes over a short transition zone into a shaft having asubstantially circular cross-section. Thus, the sleeve of a snow ringneed not be subjected to any modifications as compared to the currentlyavailable solutions.

The longitudinal pole shaft may comprise a top end and a bottom end,wherein the radius (R) of the pole shaft is gradually decreasing fromthe top end towards the bottom end.

The ski pole may comprise a hand grip mounted to the top end of thelongitudinal pole shaft.

At a distance from the bottom end of the pole shaft, the pole shaft maybe provided with a section with a slightly distorted diameter comparedto the section immediately preceding and following said distorteddiameter section of the pole shaft.

This diameter distorted section may function as a friction increasingfeature to enhance fixation of a replaceable means for limiting thesinking of the ski pole into ground surfaces, such as a disc structureor a snow guard, when the ski pole is used for skiing or walking.

In one embodiment, the diameter distorted section may have a lengthalong the ski pole of about 5-40 mm, more preferably about 10-30 mm, andmost preferably about 15-25 mm. The diameter distorted section may beplaced about 10-40 mm from one end of the ski pole of the invention,more preferably about 20-30 mm from one end, and most preferably about22-28 mm from one end of the ski pole of the invention.

A snow ring and a pole grip may be attached to the pole shaft such thatthe front part of the cross-section is directed forward in skiingdirection.

FIGURES

The description above, as well as further objects, features andadvantages of the present invention will be more fully appreciated byreference to the following detailed description of the preferredembodiment which should be read in conjunction with the accompanyingdrawings in which:

FIG. 1 shows a cross-section of the shaft of a ski pole having fourcorners and where the outer perimeter is illustrated by a line.

FIG. 2 shows a cross-section of the shaft of a ski pole having fourcorners with an inner and outer perimeter.

FIG. 3 shows the cross-section of the shaft of a ski pole in relation toa circle with radius R.

FIG. 4 shows different views of the shaft for a ski pole and thecross-sectional views at different sections of the shaft.

FIG. 5 shows a table of stiffness (span) and breaking strength testresults in relation to a version of the triangular shaped cross-section.

FIG. 6 shows a table of stiffness (span) and breaking strength testresults in relation to another version of the triangular shapedcross-section.

FIG. 7 shows a table of stiffness (span) and breaking strength testresults in relation to a cross-sectional shape of the present invention.

FIG. 8 shows a summarized table with the average test values fortriangular shape versus the four corners shape of the present invention.

FIG. 9 shows test results from wind tunnel with differentcross-sectional shapes at different speed.

FIGS. 10 a-d shows graphically the test results of FIG. 8 .

DETAILED DESCRIPTION OF THE FIGURES

The FIG. 1 shows a cross-section of a longitudinal shaft for a ski pole.The cross-sectional shape is illustrated by four lines interconnected,where the lines defines the following: a first part 3, a second part 4and two side parts 5. The side parts 5 are illustrated by dotted linesin FIG. 1 for illustration purposes.

The first part 3 may be a front part and the second part 4 may be a backpart of the cross-section of the ski pole viewed in the moving directionof the skier. The side part 5 connects the front part to the back part.

The front part 3 may be a curved portion arranged symmetric about thecenterline (CL) of the cross-section. The curved portion may be a curvedline having two ends distal from each other and connected to respectiveends of the side parts 5′, 5″ defining a corner 6 at the intersectionbetween the lines 3,5.

The side parts 5 connect the front part 3 to the back part 4 and may bea straight line with one end connected to the one end of the curved lineof the front part 3 and opposite end connected to the one end of theback part 4.

The back part 4 may be a horizontal straight line arranged symmetricabout the centerline (CL) of the cross section of the ski pole. Thelength of the back part 4 may be shorter than a distal length betweenthe ends of the front part 3 such that the side parts 5 has an outwardrise (incline outwards) when moving from the pack part 4 to the frontpart 3. The outward rise meaning the rise is directed out from thecenter of the cross-sectional shape.

FIG. 2 shows a cross-section 2 of a longitudinal shaft 1 for a ski polewith a wall thickness defining an inner and outer perimeter, the innerand outer perimeters having the same shape or substantially same shape.

The shaft 1 includes a cross-section 2 that comprises a first part 3with a curved first portion arranged symmetric about a cross-sectionalcenterline (CL) of the shaft 1, and a second part 4 with a secondportion 4 arranged symmetric about the cross-sectional centerline (CL).

The first part 3 is connected to the second part 4 by side parts 5 withside portions, each side part 5 comprises a first end 5′ connected to anend of the first part 3 and a second end 5″ connected to an end of thesecond part 4, each connection between the side parts 5 and the firstand second parts 3, 4 forms a corner 6, such that there are total fourcorners 6 in the cross-section 2 of the shaft 1.

As shown in FIG. 2 the four corners 6 may be rounded such that there areno sharp edges for better aerodynamic properties. Rounded edges may alsobe easier to manufacture using layers of carbon fibers.

In terms of strength and aerodynamics, the optimum solution for a skipole is achieved according to the invention in a manner such that thecross-section of the shaft comprises four corners 6.

The curved first portion and/or the second portion may be symmetricabout the centerline (CL). The first portion, the second portion and theside portions may all be symmetric about the centerline (CL).

The curved first portion may be a circular arc having length L anddefined by an angle θ and forms part of a circumference of a circle withradius (R). Thus, this means that all points of an outer perimeter ofthe cross-sectional shape lies at or within a circumference of circlewith radius (R).

FIG. 2 shows that the curved first portion is a circular arc with radius(R). The circle is illustrated by dotted lines and enclosing the entirecross-sectional shape 2 of the shaft 1.

The curved first portion may be the arc of a semi-circle. FIG. 3 showsthat the curved first portion may be circular arc which constitutes lessthan a semi-circle. Thus, the angle θ is less than 80 degrees.

The length of the second part 4 may be equal or less than the radius (R)of the curved first portion. This means that the cross-sectional shapegradually narrows in from the curved first portion to the second part 4.

Furthermore, the two times radius (R) of the curved first portion may beequal to the greatest width of the cross-section of the shaft. Thismeans the curved front portion defines an of a circle with radius (R),and that the greatest width of the cross-section of the shaft does notexceed the 2x radius (diameter) of the circle.

FIG. 3 also shows that the curved first portion and each of the fourcorners may all be located on or at an outer circumference of the circlewith the radius (R). Hence, each of the four corners 6 are pointslocated on or at a circumference of a circle.

The side parts and the second part may be straight, curved portions or acombination thereof. In an embodiment, the back and side portions areslightly curved portions as shown in FIGS. 2 and 3 .

The curved first portion (first part 3) may be the front part of the skipole, meaning that it is headed forward in the skiing direction. Thus,the second part 4 is the back part of the ski pole.

The second part 4 may be the front part of the ski pole, meaning that itis headed forward in the skiing direction. Thus, the curved first partis the back part 4 of the ski pole.

FIG. 4 shows different views of a shaft 1 for a ski pole and thecross-sectional 2 views at different sections of the shaft 1.

The longitudinal shaft 1 may comprise a top end and a bottom end,wherein the radius (R) or cross-sectional width of the shaft 1 isgradually decreasing from the top end towards the bottom end.

Section B-B shows a cross-section 2 of the top end of the shaft vieweddownwards towards the bottom end.

Section C-C shows a section closer towards the bottom end of the shaftwhere the cross-section of the shaft still has a significant fourcorners shape.

Wherein in the section D-D the cross-section of the shaft is graduallyadopting a circular cross-section.

Thus, the top end of the shaft of the present invention, may comprise across-section having four corners 6, and wherein the bottom end isprovided with a circular cross-section. The cross-sectional shape of thetop end of the shaft may gradually change towards the cross-sectionalshape of the bottom end.

At a distance from the bottom end of the pole shaft, the pole shaft maybe provided with a section with a slightly distorted diameter comparedto the section immediately preceding and following said distorteddiameter section 9 of the pole shaft. The section is shown in detail A,in FIG. 4 .

This diameter distorted section 9 may function as a friction increasingfeature to enhance fixation of a replaceable means for limiting thesinking of the ski pole into ground surfaces, such as a disc structureor a snow guard, when the ski pole is used for skiing or walking.

The ski pole may further be configured with features for securingattachment and correct positioning of an unsymmetrical replaceable meansfor limiting the sinking of the ski pole into ground surfaces, such as adisc structure or a snow guard, in a desired direction relative to theshape of the ski pole.

In one embodiment, the diameter distorted section 9 may have a lengthalong the ski pole of about 5-40 mm, more preferably about 10-30 mm, andmost preferably about 15-25 mm. The diameter distorted section 9 may beplaced about 10-40 mm from one end of the ski pole of the invention,more preferably about 20-30 mm from one end, and most preferably about22-28 mm from one end of the ski pole of the invention.

A snow ring and a pole grip may be attached to the pole shaft such thatthe front part of the cross-section is directed forward in skiingdirection.

The diameter distorted section of the above embodiments is primarily afeature which is designed to enhance friction when a stopper means isused to firmly fix a replaceable means for limiting the sinking of theski pole into ground surfaces, such as a disc structure or a snow guard.The stopper, which is designed to be compatible with the replaceablemeans for limiting the sinking of the ski pole into ground surfaces, isaided in its stopper function by the enhanced friction of the diameterdistorted section. Preferably, the diameter distorted section 9 may havea cross-sectional diameter less than the cross-sectional diameters ofthe sections immediately preceding and following said diameter distortedsection. However, the diameter distorted section 9 may have across-sectional diameter which is greater than the cross-sectionaldiameters of the sections immediately preceding and following saiddiameter distorted section.

The feature for securing attachment may in a desired direction of suchunsymmetrical means may be a slot placed diametrically across thecircular cross-sectional end of the ski pole as shown in detail A, inFIG. 4

This slot may also be place slightly off center, or it may be placed offcenter to such a degree that the slot is a recess. The slot maypreferably be about 1-10 mm deep, more preferably 2-8 mm deep, and mostpreferably 3-6 mm deep. However, it is contemplated that the slot ofthis embodiment may be replaced with other features for achieving thesame result, such as one or more lips on the ski pole in the same areaas the slot, or along the side of the ski pole in this area. It is alsopossible to achieve the same result with two or more slots.

In another embodiment of the ski pole of the invention, the ski pole mayhave incorporated means for enhancing the grip of the pole onto groundsurfaces. This may be achieved by fitting the ski pole with a spikestructure (not shown) in the end of the ski pole facing the ground whenit is used for skiing or walking. The spike structure may be formed fromany material which provides the material strength necessary forproviding a grip on the desired surface.

FIG. 5 shows a table of the deformation test with a version of thetriangular cross-sectional shaped shaft. Previous tests have shown thatthe triangular cross-sectional shape shaft has less span (lessdeformation) and higher breaking strength than a circular cross-sectionshape shaft.

Therefore, the test results shown in FIGS. 5 and 6 was performed ontriangular cross-sectional shapes to compare it with the new fourcorners 6 cross-sectional shape (FIG. 6 ) according to the presentinvention.

In the following tests, the four corners cross-sectional shape of thepresent invention is also referred to as “Aero” or “Triac Aero” as aworking title.

The test was performed by mounting a shaft between to supports with adistance of 800 mm between each other. The deformation test wasperformed using a pressure of 10-300 N at a center location on the shaftbetween the two supports. The deflection or span was measured for thetip and butt and entered into the table. Tests was performed on a frontside, back side and side portions. One additional side test wasperformed to the Aero shape since it has four corners 6.

A summarized comparison table is shown in FIG. 7 where the triangularshape is named as: 2.5 v2 and 2.5 v4.

From the summarized table in FIG. 8 , it is clear that the Aero shapehas surprisingly less span both for the tip and for the butt for allsides. A column for the average measurement (for 3 sides) is also shownin the table, stating that the Aero shape has increased stiffness (i.e.less pan) than the comparable triangular cross-sectional shapes.

In the last columns in FIG. 8 , the shafts where tested with a maximumload N for testing the braking strength in the transverse axis(perpendicular to the longitudinal direction) of the shafts. The test isalso referred to as the “pull to limit” test. Side 1 is here referred tothe front side (part) and side 3 referring to the back side (part). Theresults show that all sides of the four corner 6 shape (Aero) of thepresent invention, has increased breaking strength compared to thetriangular cross-sectional shape.

It may therefore, with great probability, be concluded that the Aeroshape cross-sectional shaft has less span and increased breakingstrength compared to both the triangular cross-sectional shape and thecircular (round) cross-sectional shape. In addition, as shown in thetable of FIG. 8 , the Aero shaped shaft has slightly lower weight thanthe triangular shape (we already know that the triangular shaped shaftis lighter in weight than the circular shaped). The weight is 55.39 gper meter, which is slightly lower than the weight of the triangularshape of: 55.99 g per meter and 56.66 per meter.

A test of Aerodynamics where also performed in a wind tunnel.Aerodynamics is a study of motion of air, particularly as interactionwith the cross-sectional shape of the shaft. To measure theaerodynamics, a drag coefficient is often used. The drag coefficient isa dimensionless quantity that is used to quantify the drag or resistanceof an object in a fluid environment, such as air or water. It is used inthe drag equation in which a lower drag coefficient indicates the objectwill have less aerodynamic or hydrodynamic drag. The drag coefficient isalways associated with a particular surface area.

FIG. 9 shows the test results by measuring the “coefficient of drag” xarea (Dd * A). The test was performed to different shafts havingdifferent cross-sectional shapes such as: rounded, triangular, Aero newstraight, Aero new curved.

Aero new straight shape was tested with the curved first portion in theforward direction (into the wind) and where both the second part andside parts are straight portions (“new straight”).

Aero new curved shape was tested with the curved first portion in theforward direction (into the wind) and where both the second part andside parts are slightly curved portions (“new curved”).

The shaft was tested at 30, 45, 75, 90 and 105 km/h. Relevant speedduring skiing are up to 50 km/h, since higher speed is mostly duringdownhill skiing where the poles are held in a backward direction and aretherefore not very relevant.

In addition, different angles of the shaft (angle of the wind inrelation to the shaft) have been measured such as 0, 45, 90 and 180degrees. Where the angles 0 and 45 are the most relevant angles since itis in the main moving direction of the skier (the 45 is directly fromthe side and 180 are directly from back).

The test results show that the curved first portion (circular arc) witha slightly rounded geometry of the second part and side portions, hasbetter aerodynamic properties than the triangular shape at relevantspeed and angles. The four corners 6 cross-section shape hasconsistently better aerodynamically properties compared to the circularcross-sectional shape.

The graphs in FIG. 10 a ) show that for a wind of 0 degrees (winddirectly from in front), and at speed of 30 km/h - 50 km/h, the “newcurved” cross-sectional shape (dotted lines) has the lowest drag.

The same result is shown in the graphs in FIG. 10 b ), at wind angle of45 degrees, where the “new curved” cross-sectional shape (dotted lines)has the lowest drag at the lower windspeed around 30 km/h.

Thus, one may conclude that the improved aerodynamics of the ski pole ofthe present invention, may most probably provide better pendulumcharacteristics for a skier during skiing.

To summarize, the shaft 1 for a ski pole of the present invention showsa remarkable and surprisingly combination of increased stiffness,rigidity and improved aerodynamics without increasing the weight of theshaft 1.

1. A ski pole comprising a longitudinal shaft, the shaft includes across-section that comprises: a first part including a curved firstportion arranged symmetric about a cross-sectional centerline of theshaft, and a second part including a second portion arranged symmetricabout the cross-sectional centerline, wherein the first part isconnected to the second part by side parts including side portions, eachside part comprises a first end connected to an end of the first partand a second end connected to an end of the second part (4), eachconnection between the side parts and the first and second parts forms acorner, such that there are total four corners in the cross-section ofthe shaft.
 2. The ski pole according to claim 1, wherein the curvedfirst portion is a circular arc defined by an angle θ and forms part ofa circumference of a circle with radius.
 3. The ski pole according toclaim 2, wherein the angle θ is less than 180 degrees.
 4. The ski poleaccording to claim 2, wherein a length of the second portion is equal toor less than the radius of the curved first portion.
 5. The ski poleaccording to claim 2, wherein a length of the circular arc is 3 timesthe radius, and the length of the second portion is one time the radius.6. The ski pole according to claim 2, wherein the curved first portionand each of the four corners are located on or at an outer circumferenceof the circle with the radius.
 7. The ski pole according to claim 1,wherein the second part (4) and each of the side parts are slightlycurved portions.
 8. The ski pole according to claim 1, wherein thesecond part (4) and side parts are straight portions.
 9. The ski poleaccording to claim 8, wherein the shaft comprises a top end and a bottomend, wherein the radius is gradually decreasing from the top end towardsthe bottom end.
 10. The ski pole according to claim 9, wherein the topend of the shaft comprises a cross-section according to any one ofclaims 1-8, and the bottom end is provided with a circular crosssection.
 11. The ski pole according to claim 10, wherein thecross-sectional shape of the top end of the shaft gradually changestowards the cross-sectional shape of the bottom while moving towards thebottom end.
 12. The ski pole according to claim 11, wherein at adistance from the bottom end of the shaft the shaft is provided with asection with a slightly distorted diameter compared to the sectionimmediately preceding and following said distorted diameter section ofthe shaft.